1 class Solution {
 2     public void setZeroes(int[][] matrix) {
 3         int m = matrix.length;
 4         if (m == 0)
 5             return;
 6         int n = matrix[0].length;
 7         Map<Integer, Boolean> rows = new HashMap<>();
 8         Map<Integer, Boolean> cols = new HashMap<>();
 9         for (int i = 0; i < m; i++) {
10             for (int j = 0; j < n; j++) {
11                 if (matrix[i][j] == 0) {
12                     rows.put(i, true);
13                     cols.put(j, true);
14                 }
15             }
16         }
17         for (int i = 0; i < m; i++) {
18             for (int j = 0; j < n; j++) {
19                 if (rows.containsKey(i) || cols.containsKey(j)) {
20                     matrix[i][j] = 0;
21                 }
22             }
23         }
24     }
25 }

 1 class Solution {
 2     public void setZeroes(int[][] matrix) {
 3         int m = matrix.length;
 4         if (m == 0)
 5             return;
 6         int n = matrix[0].length;
 7
 8         boolean resetFirstRow = false;
 9         boolean resetFirstCol = false;
10
11         for (int i = 0; i < m; i++) {
12             for (int j = 0; j < n; j++) {
13                 if (matrix[i][j] == 0) {
14                     resetFirstRow = i == 0 ? true : resetFirstRow;
15                     resetFirstCol = j == 0 ? true : resetFirstCol;
16                     matrix[i][0] = 0;
17                     matrix[0][j] = 0;
18                 }
19             }
20         }
21         //将除了第一行和第一列外的其他部分归零
22         for (int i = 1; i < m; i++) {
23             for (int j = 1; j < n; j++) {
24                 if (matrix[i][0] == 0 || matrix[0][j] == 0) {
25                     matrix[i][j] = 0;
26                 }
27             }
28         }
29         //将第一行归零
30         if (resetFirstRow) {
31             for (int j = 0; j < n; j++)
32                 matrix[0][j] = 0;
33         }
34         //将第一列归零
35         if (resetFirstCol) {
36             for (int i = 0; i < m; i++)
37                 matrix[i][0] = 0;
38         }
39     }
40 }